This invention relates to valve assemblies, and more particularly to an automatic air pressure relief and check valve assembly which, when used in combination with a swimming pool filter tank, permits air to be evacuated from the tank while the tank is being filled with water and automatically closes when the tank is full of water to prevent air from entering the tank and thereby preventing the water in the tank to drain to the swimming pool.
Most swimming pools include a water recirculation system where water from the pool is circulated through a filter and then returned to the pool. The filter generally comprises a water tank which contains a bed of granular filter material such as sand, or filter elements coated with diatomaceous earth, through which the pool water is forced for removing solid particles therefrom. The filtered water is then returned to the swimming pool. Water circulation is conventionally accomplished by means of an electrically driven water pump situated in the water line between the pool and the inlet side of the filter tank.
Proper maintenance of such filters requires that the tank be disassembled from time to time, for permitting maintenance of the sand bed and cleaning of the diatomaceous earth filter elements. Prior to tank disassembly, of course, the tank must be drained of water.
In swimming pool filter systems of the prior art, a manual air relief valve is conventionally attached to the upper portion of the filter tank. The air relief valve is manually opened to permit air to enter the tank so that the tank may be drained prior to tank disassembly. After the filter has been maintained and the tank reassembled, the maintenance person must assure that the relief valve is open so that air will be permitted to escape from the tank while the tank is being filled with water. When the tank becomes full, the maintenance person must manually close the valve to prevent water from escaping therethrough and to permit recirculating water pressure to be established, as well as for precluding re-entry of air into the tank when the pump is periodically shut down.